10am Thursday 7 March 2024
We welcome independent Ōrākei main sewer collapse report and accept recommendations
We have welcomed the findings of an independent report conducted by engineering consultancy WSP into the cause of the Ōrākei main sewer collapse and are focused on implementing its recommendations.
The report sheds light on factors contributing to the incident, known colloquially as the Parnell sinkhole, while also highlighting areas for improvement within our operations.
Chief executive Dave Chambers says the company openly acknowledges the impact of the incident on the environment, iwi, and community.
"When the sewer collapsed, wastewater overflowed into the Waitematā Harbour for several weeks. Understandably, this was very distressing for iwi and our community, and we apologise wholeheartedly.”
We prioritised public and environmental health in the period following the incident, swiftly initiating measures to mitigate the overflows.
"Our immediate focus was to halt the overflows and safeguard the environment. I’m incredibly proud of our staff and contractors who worked quickly to construct one of New Zealand’s largest pump stations within three weeks,” says Chambers.
We engaged WSP to conduct a comprehensive review of the incident to find its root causes and to action learnings from it.
The resulting report identified seven contributing factors to the collapse and that the interplay of all seven lead to the collapse. The factors included the condition of the pipe; extreme rainfall events in 2023; and weakened concrete blocks at the failure location.
"We are pleased to receive the detailed report. It has valuable guidance and we’re committed to implementing its recommendations," says Chambers.
The report highlights areas for improvement in sewer condition assessments and renewal practices, including enhanced inspection techniques and the development of comprehensive assessment and intervention strategies.
"We agree there is a need to lift our inspection techniques, and therefore we will be investing in more detailed inspections and profiling reports moving forward," Chambers says.
“Fortunately, the quality and capability of CCTV has improved in recent years. The type of CCTV the report recommends – which can pan and tilt – isn’t readily available in New Zealand, so we’ll be looking at the options to get it here.”
We did not wait for the report to take proactive steps to enhance its condition assessment strategy, with plans being developed for implementation by July. Additionally, we are committed to investing more in pipe renewals during the next two decades, as outlined in its latest Asset Management Plan.
“We are already ramping up our planned investment in wastewater renewals,” Chambers says. “Programme development is underway, and within the next few years we expect to be spending some $100m per year.”
The report was presented at a meeting of our Board of Directors on Tuesday 5 March, and made available to the public on Thursday 7 March. We also commissioned independent environmental impacts reports which we expect to release in the coming weeks when they are finalised.
Work to rehabilitate the damaged section of the Ōrākei main sewer well underway
Chief operations officer Mark Bourne says construction work to rehabilitate the damaged section of the Ōrākei sewer is well underway.
“We’ve been busy preparing the site so that we can start installing the new liner from mid-March, which is made of glass-reinforced plastic and will extend the life of this section of the sewer by 100 years.
“The new liner will be installed by ‘slip-lining’ – where you install a slightly-smaller diameter pipe in the old pipe, grout the space in between the new and old pipe and seal it at the ends.
“With this technique we can keep wastewater flowing through the sewer while relining work is underway.
“We’d like to thank the Parnell community for their patience while we carry out this critical work.”
We are planning to reline about 1.6 kilometres of the sewer – from close to the Parnell Train Station to the end of Logan Terrace – in the next few years. This $86.74 million investment will significantly reduce the risk of future sewer collapses in Parnell.
5am Thursday 16 November 2023 - joint statment with Ngāti Whātua Ōrākei
Rāhui over Waitematā Harbour lifted as water quality improves
Ngāti Whātua Ōrākei – the tangata whenua and ahi kā of central Tāmaki Makaurau – is holding karakia at Ōkahu Bay Thursday morning to formally lift the rāhui over Waitematā Harbour.
The rāhui was put in place by Ngāti Whātua Ōrākei on September 28 in response to the high-volume wastewater overflows caused by the sinkhole that blocked the Ōrākei Main Sewer.
Ngāti Whātua Ōrākei Trust chair Marama Royal says what has occurred resulted in a disruption to the natural systems and mauri of Waitematā. The rāhui that we are lifting today is a traditional means for recognising and managing the effects of such disruptions.
“After close consultation with Watercare, and having conducted our own assessments, we are now confident that the mauri of our cherished Waitematā has recovered sufficiently,” she says.
Royal acknowledges the collective patience and respect the community has shown by observing the rāhui.
“We thank everyone for respecting the rāhui, and as we move into this next phase, let's remember our collective responsibility as kaitiaki."
Watercare chief executive Dave Chambers says: “We’d like to extend our sincere thanks to Ngāti Whātua Ōrākei for their support, particularly over these past few weeks.
“We know the overflows were heartbreaking for so many Aucklanders, but particularly for the people of Ngāti Whātua Ōrākei as kaitiaki of the Waitematā.
“Our water quality and wider environmental programme is ongoing, but the results so far indicate the harbour is recovering incredibly well and as a result, most beaches have green water quality pins on Safeswim again, which is great news ahead of summer.
“While the impact of the overflows seems to have been highly localised, we’ll be working with other organisations to do what we can to protect and enhance our treasured Waitematā Harbour.”
Ngāti Whātua Ōrākei and Watercare are meeting with experts in environmental systems regeneration next week to begin planning for the rehabilitation of Waitematā following this event.
Safeswim.org.nz continues to be the best source of up-to-date information about water quality and other potential hazards at beaches in Tāmaki Makaurau.
1pm Friday 10 November - press release
Early results from harbour monitoring show localised impact from sinkhole incident
Early results from our environmental monitoring of the Waitematā Harbour are reassuring and indicate the impact of the overflows from the Ōrākei Main Sewer blockage seem to be localised.
It’s been three weeks since a wastewater bypass put a stop to the high-volume overflows into the Waitematā Harbour that began when a sinkhole formed above the major wastewater pipe in Parnell and blocked it when the ground caved in.
Our environmental care manager Dr Nathaniel Wilson says water sampling in the harbour and oyster sampling are key components of the environmental monitoring programme.
“Our sampling programme will continue until at least Christmas, so while it is too soon to reach conclusions, what we’re seeing so far indicates the impact of the overflows is concentrated on the area in the immediate vicinity of the overflow locations – Mechanics Bay across to Wynyard Quarter.
“The nature of the harbour means there was sufficient dispersion and dilution to significantly reduce the impact to water quality at locations further from the discharge point. This dynamic harbour environment is why most of Auckland’s swimming beaches had green water quality pins on Safeswim soon after the overflows ended.
“It also appears that most of the solid matter had settled in the pipe and didn’t come out at the overflow point. This is why we haven’t seen wastewater debris washing up on beaches or visible on the surface of the harbour.”
Routine beach and harbour inspections have now stopped, although additional Safeswim testing will continue through November.
Oyster bags strategically placed at various locations in the harbour are tested fortnightly to measure build-up of bacteria, viruses and metals.
“Shellfish sampling indicates there were high levels of bacterial and viral indicators close to the discharge location while the overflows were occurring, which is to be expected. The good news is these levels dropped significantly when the overflows had stopped.
“It’s important to note that this sampling is to complement our environmental monitoring – not to demonstrate that the shellfish is safe to eat. General health advice – as specified on the Auckland Regional Public Health Service’s website – is to avoid eating shellfish from urban areas because of the risk from a wide range of contaminants.”
Dr Wilson says while the early results indicate the impact is highly localised, we are committed to doing what it can to protect and enhance the wider Waitematā Harbour.
“We’re following guidance from Ngāti Whātua Ōrākei and hope to have conversations with other organisations that work to protect and restore the harbour.
“This could mean contributing to existing mussel bed restoration programmes and looking for opportunities to improve the areas immediately around the discharge locations.”
Update on the Ōrākei Main Sewer and bypass solution
Our head of service delivery Sharon Danks says the bypass pumping solution is working well.
“It’s been three weeks now since the high-volume overflows stopped. We do have some issues with the pumps blocking from time to time, so we are always urging our customers to only flush the 3Ps – pee, poo and toilet paper.
“We’ve also managed to partially open the ‘stoplog’ – the steel fabricated door inside Ōrākei Main Sewer – to allow low levels of wastewater flows through the pipe. This removes the risk of overflows at times of the day when flows are higher than average, and reduces the risk of overflows in wet weather.
“There are still some large boulders inside the pipe and we hope to remove these before Christmas, once all the necessary safety measures are in place.
“The design for the sewer’s repair is progressing well. We hope to have the materials for this arrive in the country before Christmas so we can start construction early in the new year.”
3pm Tuesday 17 October - press release
Wastewater bypass project completed to reduce overflows into Waitematā Harbour
A wastewater bypass solution in Parnell that will significantly reduce overflows into the Waitematā Harbour is now operational after a massive 20-day effort to get it planned and built in record time.
We began work on the bypass on Thursday September 28, after a sinkhole formed above the Ōrākei Main Sewer and the pipe was blocked when the land caved in.
Chief operations officer Mark Bourne says: “It’s been a monumental effort from our staff, contractors and suppliers to get the bypass planned, the pipes laid, the pump station chamber excavated and concreted, and have six large temporary pumps installed and tested.
“Normally this type of project would take several months to deliver, so I’m incredibly proud of the whole team involved for their hard work and dedication to this critical project.
“Knowing that this work was vital to prevent the high-volume overflows into the Waitematā Harbour has been a huge motivator for everyone involved. I’d like to pass on our sincere thanks to those inside and outside of Watercare who have helped us along the way.”
The temporary pump station can handle flows up to 600 litres per second.
“We expect that this will be sufficient to handle normal flows in dry weather. But these temporary pumps are more susceptible to blockages than our standard network pumps, so it will be more important than ever for people to only flush the 3Ps – pee, poo and toilet paper. Please don’t flush wet wipes or any other rubbish,” Bourne says.
“Just as there was prior to the sinkhole developing, in wet weather, there will still be overflows into the Waitematā Harbour. This is because some of the catchments that feed into the Ōrākei Main Sewer are historic combined stormwater/wastewater catchments. Overflows from these combined networks are commonplace in wet weather, but they will be more frequent than normal until we have wastewater flowing through the Ōrākei Main Sewer again.
“For now, the rāhui put in place by Ngāti Whātua Ōrākei for the inner Waitematā Harbour remains in place,” Bourne says. “We’ll continue to encourage people to check https://www.safeswim.org.nz/ for the latest water quality information before they head into the harbour.”
Environmental monitoring
We have sought the advice of marine environmental experts, Ngāti Whātua Ōrākei and other mana whenua, and are following their recommendations with a monitoring programme to assess the impact of the overflows on the Waitematā Harbour.
“In addition to the widespread sampling undertaken since the first week of the overflows by Auckland Council’s Safe Networks and Safeswim teams, we began a targeted daily harbour sampling regime on Wednesday October 11. These samples are being taken at multiple sites and depths and are being tested for a wide range of parameters,” Bourne says.
“We are also placing bags of oysters at locations from Westhaven to Okahu Bay. Samples from these bags will be tested every fortnight for bacteria and heavy metals. This information will supplement our data from the water sampling programme.”
We will also be carrying out routine beach inspections. So far there has not been any noticeable wastewater debris on beaches.
“We’ve engaged the Sea Cleaners Trust to carry out routine inspections of the harbour and report back to us. So far, they haven’t seen any more debris in the harbour than they normally would.”
Repairing the damaged Ōrākei main sewer
With the wastewater bypass now operational, our focus will turn to the plan to clear the remaining boulders blocking the Ōrākei Main Sewer and carry out the necessary rehabilitation to the sewer.
“We’ve been clearing the loose debris from the blockage by hydro-jetting 24/7 over the past few weeks, but what’s left in the pipe is large boulders that can’t be removed with this method,” Bourne says.
“We’re now planning how we can safely remove these boulders. We’re also firming up our plan for the rehabilitation of the section of the Ōrākei Main Sewer that’s been damaged.
“We think it could take about six months to complete this rehabilitation work. However, we expect to have wastewater flowing through the pipe again once the blockage is cleared. The work to reline the sewer can be carried out with the pipe in service.”
Cause of sinkhole under review
Watercare is in the process of engaging an engineering consultancy to review the cause of the Parnell sinkhole and subsequent Ōrākei Main Sewer blockage.
Chief executive Dave Chambers says the comprehensive review will look at all data from the sinkhole site, as well as Watercare’s historical and planned maintenance and condition assessment programmes.
“We want to find out what happened and if there’s anything that could have been done differently to prevent the sinkhole from occurring and the resulting overflows to the harbour.
“We expect the review will take several months, and we will publish the report when it’s available.
“The Waitematā Harbour is a taonga and to have these high-volume overflows going into the harbour has been terrible and understandably upsetting to many Aucklanders, as it has been to our staff. We’d like to thank Aucklanders for their patience while we’ve worked to put this bypass in place.
“We’d also like to thank our construction partners, Ngāti Whātua Ōrākei, Deputy Mayor Desley Simpson and the Waitematā Local Board for their support, and of course the local businesses and residents impacted by this work.”
4.30pm Tuesday 10 October - press release
We are making steady progress on emergency work to build a bypass pumping solution that will transfer wastewater from the manholes on either side of the Ōrākei main sewer sinkhole and pipe blockage site.
The bypass is an essential component of the work to end or significantly reduce wastewater overflows into the Waitematā Harbour as soon as possible.
Head of service delivery Sharon Danks says an important milestone was reached today with the installation of a ‘stoplog’ at a manhole near the sinkhole site.
“The stoplog is basically a steel fabricated door that seals the sewer and prevents wastewater from entering the blockage site. It’s an essential component of the bypass project but it also means that when we are in a position to finish clearing the blockage, we can do so safely – without a wall of wastewater on the other side.
“The crews on site have also been working incredibly hard on the other parts of the project. We’ve laid about two thirds of the pipe now, up St Georges Bay Rd and through Alberon Reserve.
“Excavation of the chamber that will house the temporary pump station is continuing. We encountered some concrete piles during this excavation, which slowed work a little. It’s a big job – we’re effectively making space for a two-storey house underground, with the added complication of other services that need to be relocated.
“At this stage we’re on track to have the bypass operational on October 17 but we are working to a really tight programme. Our twin priorities are reducing the overflows as soon as possible, while protecting the safety of our staff, contractors and the public.
“We’re all looking forward to having the bypass operational as soon as possible. This work is fairly disruptive for the local business community, but we’re managing to keep vehicle and pedestrian access open.
“We’d like to thank everyone for their patience while we’re doing everything we can to end the overflows into the Waitematā Harbour as soon as possible.”
When the bypass is operational, we expect it will end or significantly reduce the overflows. As some of the catchments that feed into the Ōrākei main sewer are historic combined wastewater and stormwater networks, the flow in the sewer increases in wet weather and decreases in dry weather.
“It is likely that in wet weather, there will be some overflows even after the bypass is in place – but the volume of these would be much smaller than we’re seeing now,” Danks says.
Incident controller Nigel Toms says Aucklanders are still urged to avoid swimming, fishing and recreational activities in the inner Waitematā Harbour. “Please check the https://safeswim.org.nz/ for the latest advice before venturing into the water.
“Auckland Council’s Safe Networks team is monitoring beach water quality with an extensive sampling programme in the inner harbour.
“We’ve also engaged a team of marine environmental experts to develop a monitoring programme so they can fully assess any impacts on the Waitematā Harbour once the overflows have stopped.”
7pm Monday 2 October - press release
Construction began today on our critical bypass project that will transfer wastewater from the manholes on either side of the Ōrākei main sewer sinkhole and pipe blockage site.
The bypass is an essential component of the work to end or significantly reduce wastewater overflows into the Waitematā Harbour as soon as possible.
Chief operations officer Mark Bourne says the design and route was confirmed today and work began immediately.
“Today we’ve started the site preparation and traffic management so tomorrow we can get to work laying the first sections of pipe.
“With the design confirmed and work underway, we now have a better idea on when we’re likely to complete the bypass.
“Due to the complexity and scale of the job, we don’t expect this to be completed for another two weeks.
“The position of the existing underground services is a complicating factor, and we’ll need to move an underground gas line as part of the project.
“The large pumps need to be buried underground, and we now understand it will take at least 10 days to excavate the chamber and install them. Once they’re installed, the commissioning process is another two days.
“The team at Watercare, like everyone in Auckland, wants to see these overflows end as soon as possible. Our role in the wastewater side of the business is about protecting the environment, and it’s a role we’re all passionate about. We are continuing to push ahead with work to clear the blockage in the pipe as soon as possible.
“When the bypass is operational, we expect it will significantly reduce the overflows. As some of the catchments that feed into the Ōrākei main sewer are historic combined wastewater and stormwater networks, the flow in the sewer increases in wet weather and decreases in dry weather.
“It is likely that in wet weather, there will be some overflows even after the bypass is in place – but the volume of these would be much smaller than we’re seeing now.”
Auckland Council’s Safe Networks and Safeswim teams have been conducting sampling at Auckland beaches since the overflows began on Wednesday last week, after the sinkhole above the Ōrākei main sewer widened and sent ground material tumbling into the pipe, blocking it.
When the wastewater overflows end, sampling will be undertaken to confirm water quality at Waitematā beaches has returned to normal.
Consistent with NZ Guidelines for recreational water, this will require multiple samples over a number of days that signal the water is safe for swimming before water quality alerts can be removed.
5.30pm Friday 29 September - press release
Staff and crews on site will be continuing to work around the clock this weekend and have made steady progress on solutions to the Ōrākei main sewer blockage.
Chief operations officer Mark Bourne says: “Our crews managed to remove double the amount of material yesterday than they did the previous day which is great news. They’ve been hard at work on hydro-excavation, which is essentially jetting water into the blocked section and sucking loose material out with a vacuum sucker truck. Hydro-excavation will continue over the weekend.
“At the sinkhole site, yesterday we completed excavation around the top of the hole to make it safe. Today the team has been spraying a concrete-like product on the slope of the hole which helps to prevent more material from falling in.
“We’ve also managed to source the pipe for the overland bypass solution that we’ll be building next week to transfer wastewater between the manholes either side of the blockage.
“We have sourced some of this pipe from one of our existing projects, and the rest is being manufactured this weekend by a company in Whanganui that’s working hard to support Tāmaki Makaurau at this challenging time.
“We’re also making progress on route planning and expect to start building the pipe early next week.
“This bypass solution is a massive undertaking, and the target we’ve put in place – 10 days time – is certainly ambitious. But we’ll be doing everything humanly possible to meet this target.
“Our beautiful Waitematā Harbour is a taonga and – like everyone else in Auckland – we are saddened by this unfortunate event. Please be assured we have hundreds of people – staff, contractors, suppliers and supporters – doing everything in their power to put an end to the overflows as soon as possible.”
Crews spraying a concrete-like product on the slope of the hole which helps to prevent more material from falling in.
12.30pm Thursday 28 September - press release
Our team say there’s no quick fix for the blockage in the Ōrākei main sewer and is warning Aucklanders that the no-swim warning for the Waitematā Harbour will likely be in place for up to 10 days.
Chief operations officer Mark Bourne says the latest CCTV inspections indicate the blockage of debris in the pipe extends for about 25 metres.
“Our crews have been working around the clock to try to clear as much of the blockage as possible. Last night, by hydro-excavation – jetting water into the blockage – we were able to clear about three tonnes of material. But with a 25-metre section of debris, it’s looking very unlikely that we’ll be able to clear the full blockage without major excavation.
“With that in mind, while we’ll continue with hydro-excavation, we’re now also planning to install an overland bypass pumping solution that will transfer wastewater between the manholes on either side of the blockage. This will serve two purposes – it will reduce the pressure on the pipe network and minimise the volume of overflows as much as possible.
“I need to stress though, setting up a bypass of this size is a massive undertaking. It’s likely to be the largest wastewater bypass solution that’s ever been put in place in New Zealand.
“We are planning to have this operational within the next 10 days and our teams will be working around the clock to make this happen.
“Until then, our recommendation for Aucklanders will be to avoid swimming, fishing and recreational activities in the Waitematā Harbour as there are currently ongoing overflows near the CBD.”
Bourne says once the bypass solution is in place, the focus will be on large-scale excavation to remove what’s left of the blockage.
“Clearing the blockage itself could take several weeks and the pipe’s long-term repair is likely several months away. This means the temporary bypass solution may be in place for quite some time.
Watercare staff this morning joined Ngāti Whātua Ōrākei at Okahu Bay for a ceremony that included the placement of a rāhui on the Waitematā Harbour, which reinforces the recommendation to avoid fishing, swimming and recreational activities in the harbour.
“We acknowledge Ngāti Whātua Ōrākei’s role as tangata whenua and thank them for their support in the protection of te Waitematā and the community of Auckland.”
1pm Wednesday 27 September - press release
The flood and cyclone earlier this year is potentially still impacting our city, with a large sinkhole having developed on a private property in Parnell. On Monday afternoon, we were alerted to a hole in the ground by a company undertaking work at a site on St Georges Bay Rd, above the Ōrākei Main Sewer.
This 2.1m-diameter brick sewer, approximately 13 metres underground, serves large parts of central and west Auckland. The top of the wastewater pipe has collapsed.
Chief operations officer Mark Bourne says we undertook immediate steps yesterday to address this situation, including seeking advice from geotechnical engineers to guide our approach for repairs.
“Our crews worked until early this morning, removing material to strategically widen the tomo, stabilising the ground and preventing further material entering the pipe.
“Unfortunately, the situation has worsened with the sewer becoming completely blocked this morning, which may be causing overflows elsewhere in the network.
“Our crews on site are currently working with a large excavator to further widen the top of the tomo to remove the debris causing the blockage.
“Safety is our number one priority. The ground near the sinkhole is unstable so we have established an exclusion zone around the site to ensure the safety of the public, staff and contractors.
“We’re working hard to confirm any overflow locations and to minimise any environmental impact as much as possible.
“As we haven’t yet been able to confirm overflow locations, we have raised black water quality pins on Safeswim and are urging Aucklanders to avoid swimming, fishing and recreational activity in the Waitematā Harbour. Warning signs are currently being erected at all inner-city beaches.
“Once the blockage has been cleared, wastewater will be able to flow through the pipe again and we’ll progress with planning for its repair.